236 SEE— FURTHER RESEARCHES ON [April 24, 



Mesozoic rocks to each other, we may infer that several renewed uplifts, 

 after successive denudations, took place before the beginning of Tertiary- 

 times, but without any general and extensive plication. A large part of the 

 range was certainly submerged during the Eocene period under the waters 

 of the wide sea which spread across the center of the Old World, and in 

 which the nummulitic limestone and flysch were deposited. But after that 

 period the grand upheaval took place to which the present magnitude of the 

 mountains is chiefly due. The older Tertiary rocks, previously horizontal 

 under the sea, were raised up into mountain-ridges more than 11,000 feet 

 above the sea-level, and together with the older formations of the chain, 

 underwent colossal plication and displacement. Enormous slices of the 

 oldest rocks were torn away from the foundations of the chain and driven 

 horizontally for miles until they came to rest upon some of the newest 

 formations. The thick Mesozoic groups were folded over each other like 

 piles of carpets, and involved in the lateral thrusts so as now to be seen 

 resting upon the Tertiary flysch. So intense was the compression and shear- 

 ing to which the rocks were subjected that lenticles of the Carboniferous 

 • series have been folded in among Jurassic strata, and the whole have been 

 so welded together that they can hardly be distinguished where they meet, 

 and what were originally clays and sands have been converted into hard 

 crystalline rocks. It is strange to reflect that the enduring materials out 

 of which so many mountains, cliff's, and pinnacles of the Alps have been 

 formed are of no higher geological antiquity than the London Clay and 

 other soft Eocene deposits of the south of England and the north of France 

 and Belgium: At a later stage of Tertiary time, renewed disturbance led 

 to the destruction of the lakes ini which the molasse had accumulated, and 

 their thick sediments were thrust up into large broken mountain masses, 

 such as the Rigi, Rossberg, and other prominent heights along the northern 

 flanks of the Alps. Since that last post-Eocene movement, no great orogenic 

 paroxysm seems to have affected the Alpine region. But the chain has been 

 left in a state of unstable equilibrium. From time to time normal faults 

 have taken place whereby portions of the uplifted rocks have sunk down for 

 hundreds of feet, and some of these dislocations have cut across the much 

 older and more gigantic displacements of the thrust-planes (Fig. 282). At 

 the same time continuous denudation has greatly transformed the surfaces 

 of the ground, so that now cakes of gneiss are left as mountainous outliers 

 upon a crushed and convoluted platform of Tertiary strata. Nor, in spite 

 of the settling down of these broken masses, has final stability been attained. 

 The frequent earthquakes of the Alpine region bear witness to the strain 

 of the rocks underneath, and the relief from it obtained by occasional rents 

 propagated through the crust along the length of the chain." 



In view of the explanation of the folding' of the Alps given 

 in § 28, we need not comment on these views. They confirm the 

 theory oiitHned in this paper, that the plications of all such chains 

 must be sought in the actions of the sea, and mainly while the 



